Dual-Mode Multi-Vortex Beam Generation Method Utilizing the Elliptical Array

Ever since the concept of the orbital angular momentum (OAM) was first introduced to the radio frequency in 2007, the antenna arrays for OAM generation have become the most “classic” method. However, there are still many challenges for the traditional antenna arrays, such as limited OAM mode number, low aperture's efficiency, complex feeding networks, etc. In this paper, a new method for multi-vortex beam generation is proposed using the elliptical array. An intuitional explanation for this design methodology is given with the aid of the concept of projection. Besides, the grating lobe phenomenon for vortex beam is studied for the first time. Several numerical results are presented to support our ideas. The method proposed might be useful for real antenna system design.